Looking for a suitable wireless access point for Linux

Q Following some recent advice I bit the bullet and bought a Dell laptop, the Inspiron 1525. It's happily running Ubuntu, and it's the first wireless device I have. So I need an access point. I already have a network in place, with a LAMP setup that's also a firewall and router to the internet. But I don't know where to start with the wireless. I googled and read product reviews, and I see a lot of devices that are an access point, switch and router or just an access point, but I can't figure out where that sits in my network. Is it possible to use an access point/switch device, like (for example) the Linksys WRT54GL to extend my wired network to wireless via the switch function? I know it's a router, but I want it to be a switch, so that the wireless is in the same 192.168.2.0/24 segment. If I install it as a router, I'd have to go through double NAT to the internet, which makes it impossible to connect to a remote desktop at work from home. Would it work through a concrete floor so that the wireless extends to downstairs?

A You need a plain wireless access point. This connects to your existing wired network at your router or switch, and extends it into the wireless realm. While it would be possible to use an all-in-one router and access point (and even modem) for this task, you would need to disable the bits you don't need, making it a more complex setup than using a plain access point. The access point handles the wireless connection and encryption, while everything else uses your existing wired setup. One thing to watch out for is that wireless access points generally have a built-in DHCP server.

If you have an existing DHCP server in your router, disable the access point's DHCP as having two independent DHCP servers on a network is asking for conflicts. All the access points I've used have a web interface (which you have to access for the wired network) where you can turn off DHCP. Range is a difficult topic, anything thicker than air between the access point and laptop will reduce your range to an extent. Also, most omnidirectional antennae are only omnidirectional in the horizontal plane with limited vertical coverage; a higher gain antenna increases this effect. A patch antenna is a directional device that allows you to adjust horizontal and vertical coverage, although some experimentation is required to find the best position. Since you may need to replace your antenna to improve coverage, make sure the access point you choose has a removable antenna. Most do, but there are a few with fixed antennae.